Search

Speech comprehension relies on auditory as well as visual information, and is enhanced in healthy subjects, when audiovisual (AV) information is present. Patients with schizophrenia have been reported to have problems regarding this AV integration process, but little is known about which underlying neural processes are altered. Functional magnetic resonance imaging was performed in 15 schizophrenia patients (SP) and 15 healthy controls (HC) to study functional connectivity of Broca's area by means of a beta series correlation method during perception of audiovisually presented bisyllabic German nouns, in which audio and video either matched or did not match. Broca's area of SP showed stronger connectivity with supplementary motor cortex for incongruent trials whereas HC connectivity was stronger for congruent trials. The right posterior superior temporal sulcus (RpSTS) area showed differences in connectivity for congruent and incongruent trials in HC in contrast to SP where the connectivity was similar for both conditions. These smaller differences in connectivity in SP suggest a less adaptive processing of audiovisually congruent and incongruent speech. The findings imply that AV integration problems in schizophrenia are associated with maladaptive connectivity of Broca's and RpSTS area in particular when confronted with incongruent stimuli. Results are discussed in light of recent AV speech perception models., (Copyright © 2013 IBRO. Published by Elsevier Ltd. All rights reserved.)

Early blindness results in occipital cortex neurons responding to a wide range of auditory and tactile stimuli. These changes in tuning properties are accompanied by an extensive reorganization of the occipital cortex that includes alterations in anatomical structure, neurochemical and metabolic pathways. Although it has been established in animal models that neurochemical pathways are heavily affected by early visual deprivation, the effects of blindness on these pathways in humans is still not well characterized. Here, using (1)H magnetic resonance spectroscopy in nine early blind and normally sighted subjects, we find that early blindness is associated with higher levels of creatine, choline and myo-Inositol and indications of lower levels of GABA within the occipital cortex. These results suggest that the cross-modal responses associated with early blindness may, at least in part, be driven by changes within occipital biochemical pathways., (Copyright © 2013. Published by Elsevier Ltd.)